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Model weights

How models work Last reviewed 2026-06-11

Definition The numerical parameters—often billions of them—inside a neural network that encode everything the model learned during training. The weights are the model: whoever holds them can run or modify it.

In more depth

Training gradually adjusts the weights until the model performs well; afterward, the weights are a large file of numbers that, with the right software, reproduces the model's behavior anywhere. Open-weight models publish this file for anyone to download, while closed models keep weights on the provider's servers. Weights do not store documents verbatim the way a database does, although models can sometimes memorize and reproduce fragments of training data.

Related terms

Training dataOpen modelClosed modelFine-tuning

About the editor: MHSB Solutions, Research desk. MHSB Solutions is not a law firm. This glossary is educational information, not legal advice.

Educational information, not legal advice. AI terminology and tools change quickly; definitions reflect usage as of the last-updated date. For what bar associations and courts actually require of lawyers using AI, see legalaicompliance.help and consult a licensed attorney in your jurisdiction.